In order for a mechanical seal, an example of a sliding component, to maintain sealing performance for the long term, it must satisfy both conflicting conditions of “sealing” and “lubrication.” In particular, in recent years, for environmental measures or the like, there has been an increasing demand for a further friction reduction to reduce mechanical loss while preventing leakage of sealed fluid. In a technique to reduce friction, various textures are given to sliding surfaces to achieve these. For example, one known texture is the alignment of dimples on a sliding surface.
For example, in the invention described in JP H11-287329 A (hereinafter, referred to as “Patent Document 1”), by forming a large number of dimples of different depths on a sliding surface, load capacity is stabilized because load capacity due to a fluid bearing pressure produced in fluid interposed between the sliding surface and an opposing sliding surface during sliding decreases in some dimples with changes in fluid temperature but increases in other dimples, so that an effect of maintaining constantly good sliding performance regardless of changes in temperature is obtained.
In the invention described in JP 2000-169266 A (hereinafter, referred to as “Patent Document 2”), a sliding surface is formed by evaporating a hard coating on a surface of a substrate material made of a sintered ceramics material, and the sliding surface is configured to have a large number of dimples, so that wear resistance is improved and liquid lubricity by the dimples is improved.